Definition: an animal that excavates holes or tunnels into soil or benthic sediment to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Inhabited burrows function as a refuge, protecting the inhabitants from predation and environmental extremes. They provide physical support for the digging and feeding activities of the burrow inhabitants. The harsh chemical environment deep in aquatic burrows must be counteracted by active or passive irrigation of burrow water.
Definition: Downward conveyors exhibit a feeding strategy opposite to that of upward conveyors. Vertically oriented head-up feeders actively select and ingest particles at the surface and egest these non-locally as faeces in deeper sediment strata